title: Post exercise changes in compartmental body temperature accompanying intermittent cold water cooling in the hyperthermic horse.
abstract: Whereas the efficacy of cold water cooling of horses has been demonstrated by several studies, the dynamics of temperature changes within and between compartments (primarily muscle, blood [core], skin and deep core [rectal]) have not been investigated. Changes in body temperature associated with cold water cooling were investigated in the hyperthermic horse. Muscle (TMU), pulmonary artery (TPA), rectal (TREC), tail-skin (TTSK) and coat surface (TCOAT) temperatures, were monitored continuously in 5 Thoroughbred horses during and after exercise in hot humid (30 degrees C and 80% RH) conditions on a treadmill. Horses were cooled in the hot humid environment with cold water (approximately 6 degrees C) for 6 30 s periods. Between each 30 s cooling period the horses stood for 30 s. A total of 180 l of cold water was applied. Horses were monitored for a further 4 min following the final cooling period. From the end of exercise to the end of the final cooling (6.5 min), mean (+/- s.e.) rates of decrease for TTSK and TPA were similar (0.8 +/- 0.1 and 0.8 +/- 0.1 degrees C/min, respectively). The effects on TMU and TREC were less marked, with average rates of 0.2 +/- 0.1 and 0.0 +/- 0.1 degrees C/min, respectively. During the first 4 min of cooling, TPA fell during the 30 s period of water application and rose during each 30 s period of standing. When TPA fell below approximately 36.5 degrees C, these variations were suppressed and TPA rose steadily, despite continued applications; TREC and TMU continued to fall, although less rapidly than before. These observations are consistent with the onset of skin vasoconstriction at low TPA. The mechanism is mediated through a cooling of circulating blood volume providing a greater capacity for heat transfer between muscle and circulation. Intermittent application of cold water (approximately 6 degrees C) improves heat removal without apparent deleterious effects and is well tolerated. Even when hypothermia develops (based on TPA), muscle and rectal temperatures continue to fall.
authors.affiliation: Centre for Equine Studies, Animal Health Trust, Suffolk, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Marlin
authors.forename: C M
authors.initials: CM
authors.lastname: Scott
authors.forename: C A
authors.initials: CA
authors.lastname: Roberts
authors.forename: I
authors.initials: I
authors.lastname: Casas
authors.forename: G
authors.initials: G
authors.lastname: Holah
authors.forename: R C
authors.initials: RC
authors.lastname: Schroter
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D003080:Cold Temperature; D004777:Environment; D005260:Female; D005334:Fever / Q000503:physiopathology / Q000628:therapy / Q000662:veterinary*; D006339:Heart Rate / Q000502:physiology; D006734:Horse Diseases / Q000503:physiopathology / Q000628:therapy*; D006736:Horses; D006813:Humidity; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011651:Pulmonary Artery / Q000502:physiology; D012119:Respiration / Q000502:physiology; D012881:Skin Temperature / Q000502:physiology; D013817:Thermography / Q000379:methods / Q000662:veterinary; D013997:Time Factors; D014661:Vasoconstriction / Q000502:physiology; D014867:Water
chemical_list: D014867:Water